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  <title>Sets whether this cursor will wait for a while for a tailable cursor to return more data</title>

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</div><hr /><div id="mongocursor.awaitdata" class="refentry">
 <div class="refnamediv">
  <h1 class="refname">MongoCursor::awaitData</h1>
  <p class="verinfo">(PECL mongo &gt;=1.2.11)</p><p class="refpurpose"><span class="refname">MongoCursor::awaitData</span> &mdash; <span class="dc-title">Sets whether this cursor will wait for a while for a tailable cursor to return more data</span></p>

 </div>

 <div class="refsect1 description" id="refsect1-mongocursor.awaitdata-description">
  <h3 class="title">说明</h3>
  <div class="methodsynopsis dc-description">
   <span class="modifier">public</span> <span class="type"><a href="class.mongocursor.html" class="type MongoCursor">MongoCursor</a></span> <span class="methodname"><strong>MongoCursor::awaitData</strong></span>
    ([ <span class="methodparam"><span class="type">bool</span> <code class="parameter">$wait</code><span class="initializer"> = true</span></span>
  ] )</div>

  <p class="para rdfs-comment">
   This method is to be used with tailable cursors. If we are at the end of
   the data, block for a while rather than returning no data. After a timeout
   period, we do return as normal.
  </p>
 </div>


 <div class="refsect1 parameters" id="refsect1-mongocursor.awaitdata-parameters">
  <h3 class="title">参数</h3>
  <p class="para">
   <dl>

    
     <dt>

      <em><code class="parameter">wait</code></em>
     </dt>

     <dd>

      <p class="para">
       If the cursor should wait for more data to become available.
      </p>
     </dd>

    
   </dl>

  </p>
 </div>


 <div class="refsect1 returnvalues" id="refsect1-mongocursor.awaitdata-returnvalues">
  <h3 class="title">返回值</h3>
  <p class="para">
   Returns this cursor.
  </p>
 </div>


 <div class="refsect1 errors" id="refsect1-mongocursor.awaitdata-errors">
  <h3 class="title">错误／异常</h3>
  <p class="para">
   Throws <a href="class.mongocursorexception.html" class="classname">MongoCursorException</a> if this cursor has started iterating.
  </p>
 </div>


 <div class="refsect1 examples" id="refsect1-mongocursor.awaitdata-examples">
  <h3 class="title">范例</h3>
  <div class="example" id="example-1446">
   <p><strong>Example #1 <span class="function"><strong>MongoCursor::awaitData()</strong></span> example</strong></p>
   <div class="example-contents"><p>
    In this example we tail the &quot;oplog&quot; and instead of sleeping during every
    iteration, we set the <span class="function"><strong>MongoCursor::awaitData()</strong></span> option.
    <span class="function"><a href="mongocursor.hasnext.html" class="function">MongoCursor::hasNext()</a></span> will now block until there is
    more data available.
   </p></div>
   <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br />$m&nbsp;</span><span style="color: #007700">=&nbsp;new&nbsp;</span><span style="color: #0000BB">MongoClient</span><span style="color: #007700">(&nbsp;</span><span style="color: #DD0000">'mongodb://localhost:13000'</span><span style="color: #007700">,&nbsp;array(&nbsp;</span><span style="color: #DD0000">'replSet'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #DD0000">'seta'&nbsp;</span><span style="color: #007700">)&nbsp;);<br /></span><span style="color: #0000BB">$c&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">$m</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">local</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">selectCollection</span><span style="color: #007700">(&nbsp;</span><span style="color: #DD0000">'oplog.rs'&nbsp;</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$cursor&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">$c</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">find</span><span style="color: #007700">(&nbsp;array(&nbsp;</span><span style="color: #DD0000">'ns'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #DD0000">'demo.article'</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'op'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #DD0000">'i'&nbsp;</span><span style="color: #007700">)&nbsp;);<br /></span><span style="color: #0000BB">$cursor</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">tailable</span><span style="color: #007700">(&nbsp;</span><span style="color: #0000BB">true&nbsp;</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$cursor</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">awaitData</span><span style="color: #007700">(&nbsp;</span><span style="color: #0000BB">true&nbsp;</span><span style="color: #007700">);<br /><br />while&nbsp;(</span><span style="color: #0000BB">true</span><span style="color: #007700">)&nbsp;{<br />&nbsp;&nbsp;&nbsp;&nbsp;if&nbsp;(!</span><span style="color: #0000BB">$cursor</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">hasNext</span><span style="color: #007700">())&nbsp;{<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #FF8000">//&nbsp;we've&nbsp;read&nbsp;all&nbsp;the&nbsp;results,&nbsp;exit<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #007700">if&nbsp;(</span><span style="color: #0000BB">$cursor</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">dead</span><span style="color: #007700">())&nbsp;{<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;break;<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;}<br />&nbsp;&nbsp;&nbsp;&nbsp;}&nbsp;else&nbsp;{<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(&nbsp;</span><span style="color: #0000BB">$cursor</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">getNext</span><span style="color: #007700">()&nbsp;);<br />&nbsp;&nbsp;&nbsp;&nbsp;}<br />}<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</code></div>
   </div>

  </div>
 </div>


 <div class="refsect1 seealso" id="refsect1-mongocursor.awaitdata-seealso">
  <h3 class="title">参见</h3>
  <p class="para">
   MongoDB core docs on <a href="http://docs.mongodb.org/manual/tutorial/create-tailable-cursor/" class="link external">&raquo;&nbsp;tailable cursors</a>.
  </p>
  <p class="para">
   <ul class="simplelist">
    <li class="member"><span class="function"><a href="mongocursor.tailable.html" class="function" rel="rdfs-seeAlso">MongoCursor::tailable()</a> - Sets whether this cursor will be left open after fetching the last results</span></li>
   </ul>
  </p>
 </div>

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